Thermal printing utilizing thermal print heads to produce alpha-numeric or other characters on thermally sensitive paper drawn across the print head surface is well known. The characters are formed by selectively energizing one or more resistors spaced across a printing element which comes into contact with the thermally sensitive paper. When the resistors are energized, the electrical current causes them to radiate thermal energy which marks the thermally sensitive paper adjacent the resistor. By controlling which resistor is energized at any given moment, patterns of dots are formed on the thermally sensitive paper which produces the desired characters.
Several attempts have been made to manufacture a low cost and reliable thermal print head. Due to the heat generated by the printing element resistors, the print head must be properly designed to control the thermal energy that is generated. In addition, since the heat sensitive paper is advanced across the surface of the print head and resistors, the print head must be replaceable without great expense, once the resistors and print head wear out.
Attempts at manufacturing such a print head include laminating a number of individual elements into a single unitary print head. However, since the printing element containing the resistors is not easily testable without being assembled into the finished print head, new print heads containing defective printing elements must be discarded since the printing element cannot be repaired once laminated into the print head.
Additionally, there is a consideration that the printing element containing the resistors may be a precision, high resolution print head necessitating special manufacturing and assembly techniques while adjacent support and circuit members could be manufactured with considerably different processing techniques or reduced special handling.